It is now common practice to dispense semi-liquid condiments like ketchup and mustard from sealed containers. A typical system uses a diaphragm-styled pump, that is driven by CO.sub.2 gas to pull the condiment from the container and propel it through a tube to a dispenser. Dispensers are typically simple orifice and seal configurations where the seal is lifted off an orifice to allow the flow of product and returned by a spring when the actuator is released. Some systems have been developed which use various components to accomplish different goals such as dispensing in patterns and timing the dispense to provide for portion control.
A second type of system is used to dispense condiments in exact portions by the use of "volumetric" pumping. This type of pump has a cylinder that is filled with condiment and when activated a piston forces the condiment past a non-return valve and through a tube to the condiment dispenser. The stroke of the piston is limited to allow the precise adjustment of the amount of condiment dispensed. Depending on the maximum size of the portion required the portion can be regulated with an accuracy of (+/-) 1%.
Each of these systems have distinct advantages. The diaphragm pump can dispense condiments over longer distances than the piston pump. The diaphragm pump is a "demand" pump in that it will only pump when the outlet pressure falls, then it will simply pump until the pressure at the outlet is enough to keep it from pumping. The diaphragm pump cannot accurately dispense condiments by itself. Separate control mechanisms like solenoids and timers are required to control the portion size. These various options present problems since they operate independently of the desired final objective which is to provide correct condiment portioning. If the pressure applied to the pump varies the portion will vary.
It is known that the piston type pump is the best portioning device. It has accurate portion control and the dispensing speed can be adjusted to accommodate a particular application. Unfortunately it has a distinct disadvantage in that the distance from the pump to the dispenser is restricted to a few feet at most. Any distance greater than this will cause a reduction in dispensing speed due to the swelling and contraction of the line carrying the product to where it is being dispensed. The pump cannot be located directly behind the dispenser as the force required to pull the product from the container spaced a distance away would be prohibitive.
It can be appreciated that with either of the foregoing systems the problems are not so much related to getting the product from the pump to the dispenser as getting the product to the pump.
The most common type of container for powered condiment dispensing is the bag-in-box format. This is a flexible bag filled with product that has a fitting attached to the bag that can be connected to a product dispensing system. The bag is designed to contain the product and to collapse as the product is used. This type of bag has been used to contain other products for many years and is a well accepted arrangement in the food service industry. This bag system means the product contained therein is subject to atmospheric pressure of 14.7 PSI absolute. The inlet of both of the aforementioned systems is required to create a vacuum to pull the products from the bag to the inlet. As the pump pulls the product from the bag the tubing from the bag to the inlet of the pump causes friction that resists the flow of the product. This resistance limits the length of this tube to about 18". Any greater length will cause a reduction in pumping efficiency that can impact negatively on the life of the pump and the quality of the product. This is the reason that a piston type pump must be located near the bag and cannot be located near or at the dispenser.
While one might conclude that an easy solution would be to combine the two types of pumping styles together in one system this is not feasible since the piston style pumps being used are not capable of holding pressure as they use only non-return valves as controls. These valves will not accept inlet pressure without allowing product to flow during non-use periods. It thus becomes apparent that for a system to incorporate the benefits of both styles of pumping systems and provide accurate portion control over relatively long distances a new and novel system is required.
It is also essential that any new powered condiment dispensing system must reduce costs, both product and labor, and at the same time increase efficiency. At the very least any new equipment must replace other equipment at a savings of space, or cost or both.